Is this Tosh Merino DK Yarn review helpful?

Love the colors ways, I'm still confused with which style of Madelinetosh's line I should use but I like all the types of yarn. I've figured out the difference between the single vs. 3-plyed yarn styles in the DK weight styles, I just can't tell what the difference is between the styles of single ply's and styles of 3-plyed. They feel and the colorways look the same when comparing the styles of yarn in the same number of ply's.